A statement released by the St George Illawarra Dragons club said the brilliant centre died a day before his 75th birthday in a southern Sydney nursing home after a long illness.

"The six-time premiership winner passed away peacefully with his family by his side after a long battle with illness, just one day short of his 75th birthday," the statement said.

Gasnier was born and raised in the St George area and began his rugby league career with local club Renown United before making his Dragons debut in 1959 where he went on to score 127 tries in 125 games during a nine-year career.

The uncle of modern star Mark Gasnier, Reg was considered one of the greatest players the game has seen, playing 39 Tests for Australia and 125 matches for the Dragons during their record-breaking 11-premiership streak of the 1950s and 60s.

"He was a great. The mighty Reg Gasnier. He was certainly in my [view] the greatest rugby league player of all time."

Warren Ryan - one of Gasnier's Saint George team-mates, lauded him as one of the all-time greats.

"He was an absolute Rolls Royce of footballers, a magnificent centre and of course he's been named in that very select group of Immortals," Ryan said.

Bob Fulton, who would also go on to become an Immortal, rued the chance of not playing alongside Gasnier.

"He was my hero when I used to come to Sydney and watch St George play at the Sydney Cricket Ground," Fulton told News Corporation.

"I remember in 1967 we both got selected in a City side together but Reg was injured and had to pull out. It would have been a career highlight to play alongside him.

"To be selected as one of the original Immortals alongside him was a humbling experience."

A number of players and rugby league identities tweeted their condolences shortly after his death.

Penrith Panthers general manager and former Blues coach Phil Gould tweeted: "RIP REG GASNIER. One of the all-time greats. Also one of my boyhood idols. Sincere condolences to family, friends and the Big Red V club".

Gasnier is survived by his wife Maureen, son Peter and daughter in-law Angelique, daughter Kellie and son in-law Peter, and grandchildren Sheri, Jack, Bryce, Erin and Mitchell.